2.2 Buildings in the UK Climate – Climate Change

1. How have CO₂ levels changed over 400,000 years?

The change in global climate is being forced by:

• increasing levels of CO₂ being released into the atmosphere from the burning of fossil fuels and
• the inability of the biosphere to mitigate the impacts of human activity.

Although levels of CO₂ have increased in the past, it is the level of concentration and rate at which they are rising that are the most notable. The widely-known “hockey stick” graph below clearly shows the relatively recent sharp rise in comparison to levels over the last 400,000 years.

In November 2015, the Met Office announced that the global concentration of CO₂ surpassed the 400ppm level and that this is likely lead to a 1ºC global average temperature change.

Measurements of atmospheric CO₂ taken at the Mauna Loa Observatory in Hawaii shows the seasonal cycle and steady rise in concentrations between 1958 and 2016. It can be seen here: http://scrippsco2.ucsd.edu.

!! July 5th 2018 update from https://www.esrl.noaa.gov/gmd/ccgg/trends/global.html

2. What impacts can we expect due to future climate?

Impact on the built environment:

Climate change could have a dramatic effect on the way we build houses in the future. Those built today might need to cope with possible extreme summer heat, increased risk of damaging storms and the risk of summer and winter flooding. As temperatures rise there is more chance of soil drying out during spring and summer. Foundations in clay soils could be at particular risk. Designers must ensure that our homes are not just efficient, comfortable and safe in today’s climate but remain so throughout their lifetime. This means that houses should be designed using weather information that represents the future climate and not just historical weather observations. Scientists are already working closely with industry experts to ensure our built environment is resilient to climate change.

Source and Required reading:

MetOffice_Guide_to_Climate_Science1

Overall, climate change equates to more energy entering the climate system and in turn that will add power to the movement of moisture around and within buildings. This increase in energy in the climate system will lead to an increased likelihood of the following weather and climate changes and resulting impacts on the built environment:

3. National and regional impact scenarios

From the table above, we can begin to imagine how climate change will require us to adapt our planning and design approaches to the built environment. The precise level of adaption required cannot be known in advance and will vary geographically across the UK.

However, the Department for Food, Environment and Rural Affairs (Defra) – in conjunction with the Met Office and several other organisations, researched and produced a set of UK Climate Projections (UKCP18) in 2018.

UKCP18 is the result of an advanced, peer-reviewed process and the data is available for use in assessing and developing solutions for the changing climate. The UKCP18 report shows modelled conditions (e.g. mean summer temperature) in low, medium and high emissions scenarios. It displays them as colour coded UK maps, which are well worth viewing (e.g. UKCP18 overview  slide set, under ‘Summary material’ on the following Met Office webpage):

Recommended reading: UKCP18 Science Overview Executive Summary
http://ukclimateprojections.metoffice.gov.uk/media.jsp?mediaid=87868&filetype=pdf

4. How the UK climate fits into the regional picture

We saw above how climate scientists believe climate change is likely to affect our climate and weather.

Now we look in a bit more detail at the UK’s climate, on which these changes will be superimposed.

Up to this point, we have seen how global weather and climate are driven by the following:

• Solar radiation
• Angle of globe relative to the sun creating seasonal differences
• Wind inducing effect of the Earth’s rotation
• Landscape and humidity

These forces combine to create distinct long term patterns of weather or climate.

Across the globe there are 6 types of climate classifications: equatorial; arid; mediterrrainian; snow; polar; temperate. The UK has a ‘temperate’ climate, as explained below by the Met Office:

“The ‘temperate’ classification covers a range of climates from Mediterranean-type climates and humid, subtropical zones to maritime climates influenced by the oceans — like ours in the UK. The UK has a typical maritime climate, where temperatures are quite moderate although hot summer days and cold winter nights still occur. Summers in maritime climates can be hot, warm or cool. In the UK we have what’s considered to be a warm summer, whereas in Iceland the season is classified as cool.”

Source: MetOffice_Guide_to_Climate_Science1

The UK is an island and the surrounding seas, with their high thermal capacities, have a moderating effect on the climate because they absorb and release large amounts of solar radiation.

Absorbing the solar energy helps to keep the UK’s summer temperatures low and also means that winter temperatures are much warmer than other inland locations at similar latitudes. (Compare the climates of London and Dresden at 51º North, or Edinburgh and Moscow at 56º North.)

The unique position of the UK and the resulting moderating influence of the sea around it on the climate is important to keep in mind when reviewing advice on retrofit in Europe or the USA.

Additional information:

Why the UK Climate is milder

Being an island means that the UK, although in the higher latitudes, close to the arctic polar zone, has a milder climate than many of its counterparts on the same latitude. The latitude for most of the UK (excluding the Channel Islands and Shetland), is indicated in the image above by the red band, is between 50-60 degrees North.

The UK is located with in same range of latitudes to much colder regions like Canada, Northern Europe and Russia. London, at 51 degrees N, is on a similar latitude to Dresden, for example and some 5 degrees to the north is Edinburgh, on a very similar latitude as Moscow. However, the combination of maritime conditions and air currents many miles above the Earth’s surface keep the UK climate milder than the continental and North American locations that share the same latitudes.

Source: http://www.worldatlas.com/webimage/testmaps/latslongs.htm (no longer available)

These fast moving air currents in the 5-7 miles above the earth, are known as the jet stream. In the northern hemisphere the jet stream generally flows from (south) west to (north) east. The series of images below show how the jet stream it can keep colder polar air and weather further north of the UK – creating much milder conditions than other locations around the globe on similar latitudes. The final image shows a shift in the jet stream can trap cold polar air over the UK.

Atlhough the jet stream is naturally variable, a recent study shows that the jet stream’s path has become longer and more meandering, resulting in longer spells of weather. It is speculated that this change could be related to increases in the loss of sea ice in the arctic and the resulting release of heat from this activity. Changes in the jet stream patterns and location can dramatically alter typical weather patterns and result in extended periods of cold weather. The image below shows how a shift in the jet stream can lead to such a change.

Source: What is the jet stream and how does it work? http://www.metoffice.gov.uk/learning/wind/what-is-the-jet-stream Accessed 3rd April 2014

Recommended reading: http://www.bbc.co.uk/news/science-environment-26023166
(Accessed 3rd April 2014)